TCP收发——计算机网络—

TCP收发——计算机网络——day02

今天主要讲了TCP的收发

TCP发端步骤

①socket
②connect
③send
④close

TCP收端步骤

①socket
②bind
③listen
④accept
⑤recv
⑥clise

其函数主要有

connect

int connect(int sockfd, const struct sockaddr *addr,socklen_t addrlen);功能:发送链接请求参数:sockfd:套接字文件描述符addr:目的地址存放空间首地址addrlen:IP地址的大小返回值:成功返回0失败返回-1

send

ssize_t send(int sockfd, const void *buf, size_t len, int flags);功能:发送数据参数:sockfd:文件描述符buf:发送数据空间首地址len:发送数据的长度flags:属性默认为0 返回值:成功返回实际发送字节数失败返回-1

recv

ssize_t recv(int sockfd, void *buf, size_t len, int flags);功能:接收数据 参数:sockfd:套接字文件描述符 buf:存放数据空间首地址len:最大接收数据的长度flags:属性默认为0 返回值:成功返回实际接收字节数失败返回-1 如果对方退出,返回0

listen

int listen(int sockfd, int backlog);功能:监听客户端发送的连接请求该函数不会阻塞参数:sockfd:套接字文件描述符backlog:允许等待的尚未被处理的三次握手请求的最大个数返回值:成功返回0 失败返回-1

accept

int accept(int sockfd, struct sockaddr *addr, socklen_t *addrlen);功能:处理等待连接队列中的第一个连接请求该函数具有阻塞功能(如果没有人发送链接请求，会阻塞等待)参数:socket:套接字文件描述符address:存放IP地址的空间首地址addrlen:存放IP地址大小空间首地址返回值:成功返回一个新的文件描述符失败返回-1

eg：利用TCP实现跨主机的文件发送

send端

#include"head.h"int main(void)
{int sockfd = 0;FILE *fp = 0;int ret = 0;ssize_t nsize = 0;ssize_t nret = 0;char tmpbuff[4096] = {0};struct sockaddr_in srcaddr;char filename[256] = {"a.txt"};gets(filename);srcaddr.sin_family = AF_INET;srcaddr.sin_port = htons(50000);srcaddr.sin_addr.s_addr = inet_addr("192.168.1.152");sockfd = socket(AF_INET,SOCK_STREAM,0);if(-1 == sockfd){perror("fail to socket");return -1;}ret = connect(sockfd,(struct sockaddr *)&srcaddr,sizeof(srcaddr));if(-1 == ret){perror("fail to connect");return -1;}nsize = send(sockfd,filename,strlen(filename),0);if(-1 == nsize){perror("fail to send");return -1;}fp = fopen(filename, "rb");if (fp == NULL) {perror("fail to fopen");return -1;}while(1){memset(tmpbuff,0,sizeof(tmpbuff));sleep(1);nsize = fread(tmpbuff, sizeof(char), 4096, fp);if(0 >= nsize){break;}send(sockfd, tmpbuff,nsize, 0);}close(sockfd);fclose(fp);return 0;
}

recv端

#include"head.h"int main(void)
{FILE *file = NULL;ssize_t nsize = 0;ssize_t nret = 0;char name[20] = {0};char tmpbuff[4096] = {0};int sockfd = 0;int recfd = 0;int ret = 0;struct sockaddr_in recaddr;recaddr.sin_family = AF_INET;recaddr.sin_port = htons(50000);recaddr.sin_addr.s_addr = INADDR_ANY;sockfd = socket(AF_INET,SOCK_STREAM,0);if(-1 == sockfd){perror("fail to socket");return -1;}ret = bind(sockfd,(struct sockaddr *)&recaddr,sizeof(recaddr));if(-1 == ret){perror("fail to bind");return -1;}ret = listen(sockfd,10);if(-1 == ret){perror("fail to listen");return -1;}recfd = accept(sockfd,NULL,NULL);if(-1 == recfd){perror("fail to accept");return -1;}nret = recv(recfd,name,sizeof(name),0);if(-1 == nret){perror("fail to recv");return -1;}file = fopen(name,"wb");while ((nsize = recv(recfd, tmpbuff, sizeof(tmpbuff), 0)) > 0){if (fwrite(tmpbuff, sizeof(char), nsize, file) < nsize){perror("fail to write file");fclose(file);close(recfd);close(sockfd);return -1;}}close(recfd);fclose(file);close(sockfd);return 0;
}